Telephone-exchange system



@cfi. 16 1923.

A. E. LUNDELL TELEPHONE EXCHANGE SYSTEM Filed Sept. 1920 Patented 05a. 16,1923.

AIiBEN Ei LuNnELL, or n nw ivorvx, 1v. :Y.,Assie1 ro1rroWESTERN ELECTRIC COMPANY,

mcoaronnrnn, on-nEW'YonK, N. Y.,;A conrona'rionor NEW YORK.

. TELEPHONE-EXC ANGE seam A pplica tion'filed September 8, 1920. Serial No. 408,851.

To all whom it may co ncernk Be itknown that I, ALBEN' E. 'LUNDELL, a citizen of the United States, residing at New York, in the county of New York and State of New, York, have invented certain new. and useful Improvements in Telephone-EX- change Systems, of which the following is a full,'clear, concise, and exact description This invention 7 relates :chiefly to automatic telephone exchange systems and'more particularly to an automatic exchange sys-' tem of large capacity.) a i In an automatic'exchange system arranged for serving a' large'j number of'subscriber s lines, it is usualto set a train of switches to establish the connection between the calling andthe called subscribers. The first switch to be operated is usually utilized to select the particular district in which thefcalled subscribers' line is located. In-smaller systems, the first switch of the train is used to select the exchange in whichthe'called-subscribers line'is located; Since outlying dis-s tricts and distant exchanges are at varying distancesfrom the first switch, trunk lines of different lengths must be employed. These trunk lines will have various degrees of loading. This l0ading as" it is,

termedyconsists of connecting coils having suitable impedance characteristics into the circuits of thetrunksto improvethe transmission qualities when the first switch in the" train is provided with a repeating coil. It is necessarythat the ratio ofthe number of turns i'irtheprimary and secondary' wind ings of such repeating coil bemade variable, in order to accomplish good transmission,

It} is the object "of this invention to pro-1 vide-noveljand simple means for 'selecting a suitable number of turns-on the secondary winding of a' repeating coil so'that the ratio of the turns on the secondarywinding to the number oiiturns on the primary winding will be of'a correct value to provide proper transmission on any trunk to which 7 the switch,*with.which the repeating coil is as-1' sociated;'has access.

In previous systems in which means have:

been provided for varying'the ratio ofthe repeating coil windings, the result has" been accomplished under the control of the sender as .a result of'a selective operation of an automatic switch. This typeof operation places an additional burden on the sender, since it tends to complicate the the progress of the connection."

terns it is not sender circuits and also requires an additional "time interval which to accomplish the'extra selective operation. v

, a furtherobject of the invention 'to" provide asystem in which the ratio of 'the. windlngs of a repeating coilassociated with e an automatic switch may be variedin accordance with distinctive electrical char acteristics of CGSS. I I I i p A system in which the 'characteristicsof the-trunks themselves determine the repeat.

the trunks to which has ac} a systemin which the selection offra'ti'o is accomplished a under the control of a sendingf device; 5 If a change of routing is desirable it may" follow that the loading of the. trunk must'be varied. If the selection is under the control of the sender, re -design and re-wiring of. all senders may be neces.

routing: v Y p ,A'feature of the invention is the asset relays to whose contacts-thesecondary windings of a repeating coil are connected in such ingcoil ratio has additional advantages'over 'sary in order toI'accomplish'suchchange of amanner that the number of effective turns. a

of the winding maybe variably controlled in accordance with the relay combination which has been "actuated. i i

A further feature ofthe invention resides.

in the means for controlling the above men-J tioned selecting relays by means of distinctive potentials found on-the terminals of. r

the trunk selected; p i A1 additional feature of the ,inventioniis' an arrangement whereby the trunk conduc tors are p la' ced in their normal talking con dition by the removal of the distinctive elec t'rical characteristics atthei'properstage in o It is th'ought that the invention whitest? 'beunde'rstood fromthe following detailed 'coinpanying drawing v e In ;the drawing the figure description, reference-beingmade to the acshows so much of a telephone system as is necessary to an understanding of the*invention. The in-" vention has been shown applied to a semi-c automatic, system "employin power driven switches, but" since it is obviously capable of adaptation to many types of telephone sys-f disclosed. The operation of the system'is as follows;

When the subscriber'atthe' substation l to be limited to thefsystem as I ;-key set (not shown) to control the sender diagrammatically indicated in the drawing removes hisfreceiver from the switch hook,

a circuit is completed from grounded battery, left hand Winding of line relay 2, outer armature and back contact of cutoff relay 3,

through thedosed loop of the calling subscribers line, inner armature and'back contact of relay 3, right hand winding of line relay 2 to ground, Relay 2 is energized and completes a circuit from grounded battery, lamp 4;, right hand armatureand front-contact of relay 2 to ground. The resultant that the associated line is calling;-

illumination of lamp 4 informs the operator k he thereupon inserts answering plug 5 into jack 6' whereupon av circuit is Completed from grounded battery,windingof relay 7, a sleeve contacts of plug5 and jack 6, wind- 1v ingof cutoff relay 3 toground. Relays 7 (lamp 4; to: be extinguished.

and 3 -are energized. in this circuit. Relay 3,11ponenerg1z1ng, opens the circuit of l ne relay 2and thlsrelay de-energ1zes, causrng vTheloperator then depresses listening k ey line.-

8 whereupon her telephone head set isiconnected to thecaIIing line. The calling subscriber may. .now converse with the operator 1 n'd'inform her of the number of the wanted The cord circuit usedby the operator ter-' 'minates at one end in an answering plug and. in. the other man automat cswitchr In order to simplify the disclosure, it has been assumed that the switchshaft has mounted upon it but one setof brushes and that .this

setof brushes serves a contact bank containingtheterminals of 100 trunk lines arranged in 10 groups of 10 trunks each; The mechanical structure of the'switch is a readily understood simplification of the 500 point switch shown in Patent No. 1,123,696 issued January 5, 1915, to; E. B. Craft and J. N.

I Theoperator, upon ascertaining the number of the wanted line, depresses keys in a shown within the dottedrectangle at the bottom of the drawing. In practice this 7 a sender would be associated with the desired cord circuit by means of a cord finder. The

- cord finderandkey set have been omitted since they are well knownin the art,.Patent No. 1,168,319 issued January 18, 1916, to'

A. E}, Lnndel-lshowscomplete circuits for controlling a'sender of the type which ;is

'7 of the a present invention. 7

- Whenthe sequence switch (not shown).

1 associated with the sending vdevice, and

which controls sequence switch contacts 9 and 10, reaches position 2,. a circuit is-complete'd from grounded battery, winding of relay 11,,lower: right hand contact of sequence switch spring 12, conductor 13, winding ofistepping magnet 14,. contact of sequenceswitch springlO, armature and. back contact of the 0 counting relay, conductor 15, lower contact of sequence switch spring 16 to ground. Relays 11 and 14: are energ'ized in this circuit and relay 11, upon'ener- 'gizing, locksu'p through its leftfhand armature and frontcontact and the lower lefthand contact of sequence switch spring 12 to grounded conductor 13.

Relay 11 at its right hand armature and front contact completes a circuit from grounded battery power magnet of sequence switch 17 'lower'contact of sequence switch spring 18, right hand armature and front contact of relay 11 to ground, for moving this sequence switch out of position 1 and into position 2.

I In position 2 of sequence switch 17 a circuit is completed from grounded battery, winding of the up drive magnet 19, lower contact of sequence switch spring 20, right handarmature and front contact of relay 11 to ground. The energization of. magnet 19 ed ,down dueto the fact that relay 11-has now found a direct path to ground. As the brush shaft is moved upwardly relay '14 is intermittently energized to control the operation of the counting relays in the well known manner. When the O counting relay is energized the circuit through stepping. magnet 14 is permanently opened and when, a moment later, commutator brush 21 engages an insulating segment of commutator.

1 22, relay 11 isde-energized and completes acircuit from grounded battery power magnet of sequence switch 17 the upper contact of sequence switch- 18', the right hand armature andback contact of relay 11'to ground .for moving this sequence switch out of position 2 and into position 3'. The deenergization of relay 11 alsojopens the circuit of up drive magnet 19, thus causing the brush shaft tocome to rest with the brush set engaging the contact set of the first trunk in the selected roup, j p i 7 It will be' assumed that the third group of trunks has been selected. If the first trunk in this group isbusy this fact will; be indicated bythe presence of ground poten- .tial on'the test'terminalo'f suchtrunk. A

circuit is thereupon completed from ground ed battery, winding of relay .11, contact of terminal 26, and thence to ground by way of a sequence-switch contact, corresponding. to contact 27, associated with the switch which has seized such? trunk. Relay 11 issequence switch spring 27 test brush 25 test switch spring 20, right-hand armature-andfront contact of relay 11 to ground. The

energized in this circuit'and completes apcir 'cuit from grounded battery, winding of updrive magnet 19,v lower contact of sequence brush shaft is now again movedf upwardly in a trunk: hunting movement. ,As soon as test brush engages, test terminal 28, which will be assumed tobe the first idle trunk: in

the group, relay 11 'deenergizes, since no ground'potential is. found on such (test terminal. The deenergizationof relay 11 opens the circuit of-updrive magnet- 19, andcauses thebrush set to bebrought to rest'on' the terminals of the idle trunk. Thedeenergization of relay 11 also completes: afcircuitex tending from grounded battery, power magnet of sequence switch 17 upper contact of sequence switch spring 18, right-hand armature and back contact of relay 11 to ground, for moving this sequence switch outof position 4 and into position 10.

As soon as sequence switch 17 reaches position 4e},,'ground potential is supplied to test terminal byway of'test brush 25 at the lower contact of sequence switch spring-27x to render the trunk non-selectable to other hunting selector switches. i

:As soon assequence switch 17 reaches position .7, a circuit is completed"fro1n grounded Y battery, high resistance winding of relay '24 upper armature andback con-' tact of'relay29, terminal 30, brush 31, .conductor 32, lower contact of sequence switch spring 33; winding of marginal relay 34 to. ground. Due to the fact that battery has been supplied to the'tip-conductor of the] trunk through a high resistance, marginal relay 34 does not operate; Since no potential is found on the ring conducto'r'of the trunk, marginal relay 35 cannot be operated.

Relay 24 is energized in the circuit above traced and completes a circuitfrom grounded battery,-wind1ng of :relay36, ar-

mature and front, contact of relay 24 to ground. Relay 36' is energized in this circult and locks up to grounded test term nal.

As soon'as seq-uencesw1tch'17 leaves position 8, relay 24 is deenergized and completes a circuitextending from grounded battery,

winding of relay 29 armature and 'backcontact of relay 24 armature "and front contactof relay 36 to grounded test terminal. Re-' lay 29 is energized and by attracting its armatures connects through the tip and ring conductors to the main tip and ring'conductors 3.7 and 38 of the selected trunk.

Sequence switch '17 comes to rest in position 10 and the fundamental-circuit is now eX tended to the succeeding switch in the train. The fundamental circuitmay be traced from trunk conductor 37,'-'upper armature and front contact of relayi29, terminal 30', brush 31, upper right-hand contact of sequence steppingumagnet 14,-.' contact of sequence switch spring 10, armature and'back contact of the 0 counting relay, conductor 15, up-

per contact of sequence switch 16, brush 39, terminal 40, lower armature and front ,c'ontact of relay 29, ring trunk "conductor 38. Succeedingswitches in thetrain are. actuated in the Well-known manner under the control of the sender. The completion of each selective'operationwill cause the advance of the sender sequence switch.

switch spring 12, conductor 13, windingof i When the sender sequence switch reaches position 14, at which time it will be assumed that all the selective operations have been completed, a 1 circuit is completed from' grounded battery, power magnet of sequence switch 17, upper left-hand contact of sequence switch spring 41, contact of sequence relay 43 will have been energized. The circuit of the secondary winding ofthe district repeating coil may then be traced-from grounded battery," winding of supervisory relay 44, lower right-hand winding of repeatingcoil 45, it being observed-that a maximum number of turns are included. inner lower armature and back contact of relay 34, contact of sequence switch spring '42, brush. 39, terminal 40, lower armature and front contact of relay 29, trunkconductorf38, lowerleft hand winding of repeating coil 46, armature and front contact of relay '43, resistance 47, upper left-hand windingof repeating coil 46, trunkconductor 37, upper armature and frontcontact of relay 29, terminal '30, brush 31, conductor32, upper contactof sequence switch spring 33, upper armature and back contact of relay 34, upperright-hand winding of repeating coil '45' to ground,

:It is torbe observed thatthe'seleotion'of a trunk in the third group. which is characterized having reduced battery potential supply to the tip conductor of the trunk, willresult in the selection of the maximum ratio of the number of-turns in thesecond; ary winding 'ofrepeating coil'45, to'those in vthe primary winding.

ofise'quence switch 17, the

.Theconnection having been completed the subscribers may "now" converse, "it being .noted that calling supervisoryyrelay 48-was energized whengthe'operator first inserted plug 5-intojackY6.

'VVhen connectionis no longer desired,both

callingqan'd called subscribers will replace their receivers on'their switch-hooks. The

replacement of the calling subscribers ie ceiver causes the deenergization of relay 4'8" and the replacenientof the called subscribers receiver results inthed'eene'rgizatioii of'relay 453. v g p I V causesin turn the deeiiergization of relay The deenergization .oi' relay ,43

44 The operationfof the supervisory signalsnot shown controlled by relays 4:8 and ett :respectively informs the operator that connection 'is no longer desired" and -she thereupon. remoi' esplug 5 from jack 6.

The, removalofplug 5 from jack 6 interru'pts the circuitof relay 7 and thisrelay deenergizes and I completes a circuit from gifounded battery, power magnet of sequence switch 17', lower Contact of sequenceswi'tch spring 41, armature and back contact oi relay 7 to grounchi'ormoving this sequence.

switch out of position 16 and into position In position 18 of sequence switch 1 a 'cir cuit is completed from grounded battery;

.winding of down drive magnet 49', contact ingswitclies in the train takes place a 4; as; previously described.-

of sequence switch spring 50 to ground, The brush-shaft is returned toits normal position under the control of magnet 49 and as soon as commutator hrush 21 engages normalcommutatorsegment 51, a circuit is completed from grounded battery, winding per right-hand contact of "sequence switch spring 41,-- OOHlHllltittOI" segment 5-1,- coinmutatorbruslr 21 to ground, for moving se quence switch 17 out ofposition 18 and into position 1.

As soon as the brush set leaves the tenni nals of the trunk, the release of the succeedin the well-known manner. r ,j

The operation of the system if connection to a trunk in. the second group is desired will now be described; "In this case the operation of the. system will be identical with that pre-' viously described up to the selectionof an idle trunk in the second group. Sequence switch 17 .willthen be moved out of position Assoon as'sequence switch 17 reaches p0 sition 7 a circuit is completed from grounded battery, low're'sistance winding of relay 60,.upper armature-and back contactof relay 61,- terniinal 62, larush 31,; conductor 32,

lower contact of sequence switch spring 33, winding ofrelay 3 1 to ground. Since the winding of relay. 60, is of; low resistance, margin-a1 relay Saris energized in this circuit.- Relay is also energized, Relay'34,,upon

' energization, completes a locking circuit for itself extending from ground, winding of relay 34, outerlower armature and front contact of relay 34, contact of sequence switch spring 63 to grounded battery. The

" energization of relay 60 completes aJ'circuit for sleeve relay 64,-and this relay locks up to grounded test brush} 25 T in the same manner as relay 36, associated with thethird group nun-twee energized. As soon as se quence Switch 17 leaves position 8, the C1I'' cu-it' of relay 60 is open'ed'and this relay deenergizes, allowing relay 61 to beener gized overa circuitextending from grounded battery, winding of relay G1, armature and back contact of relay 60, armature and front contact of relay 64 to ground at test brush 25;; The energization of relay 61 con- 1 peating coil is connected tothe tip and ring conductors of the link circuit by way of the back contacts land arniatures of relay 35 and .the'front contacts and armatures of relay 34.

Aninspection of the drawing will show that a diiierent number'of turns has'now been included in the secondary winding of the re 7 peating coil than were previously utilized.

"It. is thought that" the operation and possibilities of the system willbe readily understood-without further description. An inspection of the arrangement of the electrical devices associated-with the trunks in the first group show that if a trunk inthis I group is seized, battery will be supplied to both relays 34 and 35 through the low resistance winding of relay 65.- In this case both' relays 34C'and 35'will be'energized andlocked up and athird repeating coil ratio I will be obtained. I

It is to be noted that the system is not limited to use in connection with automatic exchange systems but maybe employed whereever a connecting link circuit, with which a repeating coil-is associated, is used.

What is claimed is: v1

1. In a telephone exchange system, incoming lines, outgoing lines,- a link circuit to be used in establishing a connection between an incom ng 11118 and. an outgoingliiie, arepeatiiig coil associated with-said link circuit, said repeating coilcomprising 212 primary winding and a secondary winding, means for vary ing the ratio of the number of turns of said iii] secondarywinding to the number of turns of said primary winding, and means associated with said outgoing lines to: cause the operationof said ratio varying means.

2. Ina telephone exchange system. in coming lines, outgoing lines, a link circuit to be used in, establishing a connection between an incoming line and an outgoing line, a repeating coil associated with said. link circuit, saidrepeating coil comprising a primary winding and secondary winding, means for selectively controlling. the ratio of the number of turnsyof said seci terminating atone end in an automatic switch, means to operate said automatic switch to establish connection between an incoming, line and an outgoing'line, arepeatingcoil associated withsaid link circuit, said repeating coil comprising a primaryv winding and a secondary winding, means for selectively controlling the ratio of thenumber of turns of said secondary winding to the number of turns of said primary winding, said means associated with said outgoing lines to cause theoperation otsaid ratio controlling means. i

4. Ina telephone exchange system, incominglines, outgoing lines, electrical devices associated with said outgoing lines, there being differingelectricaldevices assooiated with difi'erent outgoing lines, a link circuit to be used in establishing a connectionbetween an incoming line and an outgoing line, a repeating coil associated with said link circuit, saidrrepeating coil comprising a primary winding and a secondary winding, electro-mechanisms selectively responsive to said electrical devices when c'on-- nection is established between saidlink circuit'and an outgoing line, andmeans for varying the ratio of the number of turns of said secondary winding to the number of turns of said primary winding in accordance with the response of said electro-meohanisms.

5. In a telephone system, a switching device comprising a set of movable contacts and a plurality of sets of stationary contacts, a link circuit terminating in said movable contact set, a plurality of outgoing lines terminating in said stationary. contact sets, means to supply various combinations of potentials to said stationary contacts, a repeating coil associated with said link circuit, said repeating coil comprising a primary winding and a secondary winding, and means variably responsive to said combinations ofpotentials to vary the ratio of the number of turns of said secondary winding to the number of turns of said primary winding 6. In a telephone exchange system, .a switching device comprising a set of movable contacts and a plurality of sets of stationary contacts, a link circuit terminating in said movable contact set, a plurality of outgoing lines terminating in said stationary contact sets, means to supply various combinations of potentials to said stationary contacts, a repeating coil associated with said link circuit, said repeating coil comprising a pri-' number of turnsof said secondary winding to' the numberfo'fturns of said primary winding, meanst-toremove said combinations ofpotentials froma contact set with which connection has-beenestablished, and means to maintain ,a selected ratio effective irrespeotiveof the condition of said stationary contacts.

, ,7.,In a telephone exchange system, a

switching device comprising a m'o'vable'contact set and "a plurality of sets of stationary contacts, a link circuit, terminating at one end in said movable contact set, a repeating coil associated with saidqlink circuit, said repeating coil comprising a primary winding and a secondary vwinding, apluralityof outgoing lines terminating in said stationary contact sets, means to supply different combinations of potentials to said stationary contactsets to characterize said outgoing lines, and'means variably responsive to said combinations of potentials to vary the ratio of the number of turns of said secondary winding to ,thenumber of turns of said -primary winding when connection is established fi'omfsaid linkcircuit tolan outgoing line bymeans of said switching devic a X 8. Ina telephone exchange system, incoming lines, outgoing lines, means to supply potentialsto the conductors of said outgoing lines, there being difi'ering combinations of eifective potentials associated with different outgoing lines, a link circuit to be used in establishing a connection between an incom ing line and an outgoing line, a repeatin coil associated with said link circuit, sai repeating coil comprisinga primary winding anda secondary winding, relays selectivel y responsive 'to said combinations of potential when a connection is established between said link circuit and an outgoing line, and means for varying thera'tio of the number of turns of said secondary winding .ing line and an outgoing line, :a repeating coil associated with said link circuit, said repeating coil comprising aprimary winding and a secondary'winding, relays selec tively responsive to said combinations of potentials when connection is established between said link circuit and an outgoing linef locking circuits for said relays, and means for varying the ratio of the number of turns of said'secondary winding to the number of 7 going lines, there being d'ifierlng combinations of effective potentials associated with different outgoing lines, a link circuit'to be used in establishing a connection between an incoming line and an outgoing line, a repeating coil associated with said link circuit, said repeating coil" comprising a primary winding and a secondary winding, marginal relays selectively responsive to said combinations of potential when a connection'is established between said link'circuit and an outgoing line, and means for varying the ratio of the number of turns of said second ary winding to the number of turns of said primary winding in accordance with which ones of said relays have been actuated;

11. In a telephone exchange system, a switching device comprising a set of movable contacts and a plurality of sets of stationary contact sets, a link circuit terminae ing in said movable contact set, a plurality otoutgoing lines terminating in said stationary contact sets, a group of relays associated with each outgoing line," means comprising windings and contacts of said relays to supply potentials to the contactjsets' of said outgoing lines, a repeating coil associated withsaid link circuit, said repeating coil comprising a primary winding and a secondary Winding, means variably responsive to said combinations of potentials to vary the ratio of the number of turns oi said secondary winding to the number 01 turns of said primary winding, and means including an associated relay combination to move said combination of potentials from a contact set at a desired time. I

12. In a telephone exchange system, in-

to vary the degree of modification of said voice currents, and means associated with said outgoing lines to cause the operation of said adjusting means.

In witness whereof, I hereunto subscribe myname this 23 day of Aug. A. D., 1920. ALBEN E. LU'NDELL. 

